Daarom zijn wij hier.

[hbutler]

Is “daarom” a contraction of “dat” and “waarom”?

[sindaco]

It is a contraction of “daar” and “om”

It means “therefore”

Compare

English:
Q: “Where?”
A: “There”

Dutch:
Q: “Waar”
A: “Daar”

English:
Q: “Wherefore?”/“Why?”
A: “Therefore”/“Because”

Dutch:
Q: “Waarom”
A: “Daarom”